The present invention relates to an optical circuit module. Particularly, the present invention pertains to an optical circuit module that has a collimator and is used for optical communication and to a method for assembling the same.
Japanese Unexamined Patent Publication No. 09-230169 discloses a first prior art optical circuit module that has a collimator. The first prior art optical circuit module includes two optical fibers and a capillary, which retains strands of the optical fibers. The optical fibers and the capillary are fixed to a ferrule. The ferrule is welded to a sleeve, which is welded to a first lens holder. A lens and an optical filter are fixed to the first lens holder. The lens holder is welded to a projecting block, which is welded to a housing.
In the first prior art optical circuit module, an excitation light, which is emitted from one of the two optical fibers, is converted to a parallel light with the lens. The parallel light is then emitted to the optical filter. The excitation light, which is reflected back by the optical filter, enters the other one of the optical fibers. In the first prior art optical circuit module, the sleeve and the first lens holder are adjusted while the first lens holder and the projecting block are also adjusted to couple the excitation light into the other one of optical fibers.
However, since the first prior art optical circuit module includes many parts, the size of the entire module and the cost tend to increase. Also, since many parts need to be fixed by adhesive or welding, the assembling procedure is complicated. Furthermore, since the optical filter, which is an optical device, is not located at the focal point of the lens, the coupling loss is great.
U.S. Pat. No. 5,555,330 discloses a second prior art optical circuit module that has a collimator. The second prior art optical circuit module includes a glass capillary, a lens, and a filter. The glass capillary retains two optical fibers. One end surface of the lens is secured to the end surface of the glass capillary. The end surface of the lens and the end surface of the glass capillary are attached by thermosetting resin. The filter is secured to the other end surface of the lens.
Since the end surface of the glass capillary, which retains two optical fibers, is fixed to one end surface of the lens with adhesive made of thermosetting resin, the adhesive could enter the optical path between the glass capillary and the lens. Therefore, an operator must be careful that the adhesive does not enter the optical path while fixing the capillary to the lens. This complicates the procedure for fixing the components with adhesive. Furthermore, the adhesive reliability is low.
The objective of the present invention is to provide a compact optical circuit module that is easy to assemble, and a method for assembling the same.
To achieve the foregoing objective, the present invention provides an optical circuit module including optical signal emitting means, a first sleeve, an optical device, a first lens, and optical signal receiving means. The optical signal emitting means emits an optical signal. The first sleeve includes a first end surface. The optical device includes a reflection surface. The reflection surface abuts against the first end surface of the sleeve. The first lens is located between the optical signal emitting means and the optical device. The first lens converts the optical signal emitted from the optical signal emitting means into a collimated optical signal and emits the collimated optical signal to the optical device. The optical device reflects the collimated optical signal with the reflection surface. The first lens converges the reflected collimated optical signal and generates a converged light signal. The optical signal receiving means receives the converged light signal. The first lens is fixed in the first sleeve such that the focal point of the lens aligns with the reflection surface of the optical device. The optical signal emitting means and the optical signal receiving means are fixed in the first sleeve such that the converged light signal is coupled into the optical signal receiving means.
The present invention also provides a method for assembling an optical circuit module. The optical circuit module includes optical signal emitting means, a sleeve, an optical device, a lens, and optical signal receiving means. The optical signal emitting means emits an optical signal, The sleeve has a first end surface. The optical device has a reflection surface. The reflection surface abuts against the first end surface of the sleeve. The lens is located between the optical signal emitting means and the optical device. The lens converts an optical signal, which is emitted from the optical signal emitting means, into a collimated optical signal, and emits the collimated optical signal to the optical device. The optical device reflects the collimated optical signal with the reflection surface. The lens converges the reflected collimated optical signal and generates a converged light signal. The optical signal receiving means receives the converged light signal. The assembling method includes fixing the lens in the sleeve such that the focal point of the lens aligns with the first end surface of the sleeve, adjusting the inclination angle of the optical device with respect to the central axis of the lens such that the intensity of the converged light signal received by the optical signal receiving means is maximized, adjusting the position of the optical signal emitting means and the optical signal receiving means along the central axis of the lens, and fixing the optical device to the first end surface of the sleeve and fixing the optical signal emitting means and the optical signal receiving means in the sleeve.
A further aspect of the present invention is a method for assembling an optical circuit module. The optical circuit module includes optical signal emitting means, a sleeve, an optical device, a lens, and optical signal receiving means. The optical signal emitting means emits an optical signal. The sleeve has a first end surface. The optical device has a reflection surface. The reflection surface abuts against the first end surface of the sleeve. The lens is located between the optical signal emitting means and the optical device. The lens converts an optical signal, which is emitted from the optical signal emitting means, into a collimated optical signal, and emits the collimated optical signal to the optical device. The optical device reflects the collimated optical signal with the reflection surface. The lens converges the reflected collimated optical signal and generates a converged light signal. The optical signal receiving means receives the converged light signal. The assembling method includes fixing the optical device to the sleeve such that the reflection surface abuts against the first end surface of the sleeve, fixing the lens in the sleeve such that the focal point of the lens aligns with the first end surface of the sleeve, adjusting the position of the optical signal emitting means and the optical signal receiving means along the central axis of the lens and the inclination angle of the optical signal emitting means and the optical signal receiving means with respect to the central axis of the lens such that the intensity of the converged light signal received by the optical signal receiving means is maximized, and fixing the optical signal emitting means and the optical signal receiving means to the sleeve.
Other aspects and advantages of the invention will become apparent from the following description, taken in conjunction with the accompanying drawings, illustrating by way of example the principles of the invention.